THIS IS A SHANNON AWARD PROVIDING PARTIAL SUPPORT FOR THE RESEARCH PROJECTS THAT FALL SHORT OF THE ASSIGNED INSTITUTE'S FUNDING RANGE BUT ARE IN THE MARGIN OF EXCELLENCE. THE SHANNON AWARD IS INTENDED TO PROVIDE SUPPORT TO TEST THE FEASIBILITY OF THE APPROACH; DEVELOP FURTHER TESTS AND REFINE RESEARCH TECHNIQUES; PERFORM SECONDARY ANALYSIS OR AVAILABLE DATA SETS; OR CONDUCT DISCRETE PROJECTS THAT CAN DEMONSTRATE THE PI'S RESEARCH CAPABILITIES OR LEND ADDITIONAL WEIGHT TO AN ALREADY MERITORIOUS APPLICATION. THE ABSTRACT BELOW IS TAKEN FROM THE ORIGINAL DOCUMENT SUBMITTED BY THE PRINCIPAL INVESTIGATOR. DESCRIPTION (Adapted from the Applicant's Abstract): This FIRST proposal examines the effects of learning and memory of drugs currently used to reduce self-injurious behavior and aggression in persons with mental retardation. In addition, to provide information on selectivity of psychotropic medications for reducing aberrant behaviors, the studies will concurrently measure aberrant behavior. In this way, the dose- effect functions for both behaviors can be determined and the relation of aberrant behavior reduction and cognitive functioning described. The drugs to be assessed are the typical neuroleptic thioridazine, and antiseizure medication (carbamazepine), and a selective serotonin reuptake inhibitor/antidepressant (sertraline). These drugs represent a range of drug classes with different neurochemical mechanisms and mixture of frequently prescribed, traditional medications and drugs that have been recently been used for treatment of self-injury, aggression, and property destruction. Individuals will undergo double-blind, placebo controlled trials with medications clinically indicated to reduce their severe and chronic aberrant behaviors. Primary effects of the medications on the clinically targeted behaviors will be measured with standard instruments and videotaped samples. Learning and memory will be measured using laboratory operant tasks. Learning will be assessed with a repeated acquisition of simple discrimination procedure. Short- term memory will be assessed with a delayed matching-to-sample task. Prior to the drug trial, the difficulty of these tasks will be adjusted for individual subjects to be of an intermediate level. Subjects will be assessed during a drug-free placebo baseline period, one or more doses of medication (two doses of thioridazine, three doses of sertraline, and one dose of carbamazepine) and during a second drug-free placebo period.